Rotary planographic printing press



y 12, 1964 H. FISCHER 3,132,583

ROTARY PLANOGRAPHIC PRINTING PRESS Filed June 21, 1961 United States Patent s 132 583 ROTARY PLANOGliAPllIC PRINTING PREdS Hermann Fischer, Pittsburgh, Pa, assignor to Maschinenfabrik Augsburg-Nurnberg, A.G., Augsburg, Germany,

a corporation of Germany Filed June 21, 1961, Set. No.. 118,551 Claims priority, application Germany July 9, 1960 3 Claims. (Cl. 101-142) This invention relates to. planographic or offset lithO: graphic printing and, more particularly, to arrangements in such printing whereby inking rolls and/or Water fountain rolls contact the printing plate primarily only in the area thereof having the image to be printed and some or all of such rollsare out of contact with the printing plate generally in those areas thereof which do not include the image to be printed.

As well understood in the art of planographic printing or printing by offset lithography, the printing plate is provided with a hydrophobic and oleophilic image to be printed and hydrophilic non-image or background areas of the plate surface. During printing, such a plate is first wet with water or a so-called Water fountain solution to provide an ink-repellent aqueous film over the nonimage or background areas, and is then contacted by an inking roll to deposit greasy printing ink only on the oleophilic image but not on background or non-image areas Where deposition of the printing ink is repelled or prevented by the water film thereon, and this sequence of operations is repeated for each printed copy produced by the printing press.

i There are many applications of such printing by offset lithography Where the image to be printed may actually occupy but a small fraction of the total surface area of the printing plate, and this situation may occur particularly where a single printing press of a given size is used from time to time to print on pieces of paper of different sizes. Thus, the printing plate itself must always be the full size to fit around the plate cylinder of the printing press, whether the sheets of paper being printed (and the image being printed thereon) are as large as the press will accommodate or of much smaller size requiring a printing image occupying only a small fraction of the entire lithographic plate.

Since the wetting and inking operations of the inking and fountain rolls with respect to the. printing plate are generally the same regardless of e size of the printing image thereon, some difficulty may be experienced in the inking operation in such situations, especially where the image to be inked and printed occupies but a relatively small proportion. of the entire printing plate. For example, repeated rolling contact between the ink film on the inking rolls and large areas of the water film on large or extensive unused or background areas of the printing plate may eventually cause, during the printing run, some absorption of water into the ink film on the inking rolls (nothwithstanding the essentially greasy nature of the ink) and thus-lead to dilution of the ink on the inking rolls and resultant non-uniform inking of the image to be printed.

According to this invention, however, there are provided arrangements whereby the inking rolls, and fountain rolls contact the printing plate generally only in the area thereof including the image to be printed, for example, as by the provision of cam means on the plate cylinder for raising some or all of the inking and/ or fountain roll out of contact with the printing plate during a portion of the rotation of the plate cylinder where unused or nonimage areas of the plate are adjacent the inking or fountain rolls. As further featuresof this invention there are also provided means for compensating for or avoiding slippage or speed Variations caused by such cam hoe of the inking and/ or fountain rolls individually out of contact with a plate on the plate cylinder at different angular positions therearound.

One object of this invention is to provide an arrangement of the character described in a planographic printing press whereby the inking and/ or fountain rolls thereof will be maintained outof contact with the printing plate on the plate cylinder during portions of the rotation of the cylinder where unused or imagefree areas of the printing plate are adjacent such rolls.

Another object of this invention is to provide cam means on the plate cylinder of a planographic printing press of the character described for moving and maintaining fountain rolls and/or inking rolls out of contact with the printing plate on the plate cylinder as unused or image-free areas of the printing plate pass such rolls during rotation of the plate cylinder.

A further object of this invention is to provide an arrangement of the character described whereby some or all of the fountain and inking rolls are raised out of contact with the printing plate or on the plate cylinder of an offset lithographic press during selected portions of the rotation thereof by cam means on the plate cylinder engaging the fountain or inking roll to be raised.

Still another object of this invention is to provide, in an arrangement of the character described for planographic printing presses, adjustable means on the plate cylinder for selectively raising one or more of the inking and fountain rolls out of contact with the printing plate on the cylinder during selected portions of the rotation thereof to avoid or reduce the application of ink or water fountain solution to unused or image-free areas of the printing plate and Without interfering with adequate application of both ink and water fountain solution to those areas of the plate including an image to be printed.

A still further object of this invention is to provide, in an arrangement of the character described, adjustable cam means on the plate-cylinder for raising fountain and/or inking rolls out of contact with the surface of the printing plate on the cylinder during a portion only of the rotation thereof and also including means for compensating for or avoiding surface slippage and/or non-uniform inking of the printing image on the printing plate resulting from variations in peripheral speed as between the plate cylinder and the inking or fountain rolls caused by varying effective diameter of the plate cylinder in the area of the cam means.

Other objects and advantages of this invention will be apparent from the following description, the accompanying drawing, and the appended claims.

In the drawing:

FIG. 1 is a somewhatdiagrammatic end View of the plate cylinder and inking and fountain roll arrangement of a planographic or offset printing press embodying and for practicing this invention; and

FIG. 2 is a partial side view in somewhat more detail showing a portion of the plate cylinder of FIG. 1 at one end thereof and a portion of a fountain roll raised out of contact by means embodying and for practicing this invention.

Referring to the drawing, in which like parts are designated by like characters of reference throughout the several views thereof, a roll diagram of the inking and fountain and plate cylinder portion of a lithographic or offset printing press is indicated in FIG. 1 as having a plate cylinder 10 around which is alfixed a printing plate (not shown) in conventional manner and having an image to be printed impressed thereon by conventional means. A fountain or moistening roll arrangement is indicated generally at 11 as including fountain rolls or moistening rolls 12 and 13 for applying to the surface of the printing plate on cylinder a film of water or fountain solution from roll 14, all in known and conventional manner.

An ink cylinder is shown as a source of printing ink to be applied to the image on the plate on cylinder 10, in conventional manner, as by having the ink transferred from cylinder 20 through a plurality of transfer rolls 21 to ink distributor rolls 22, and thence to inking rolls 2326 for direct application to oleophilic areas of the printing image on the printing plate around the plate cylinder 10 during rotation thereof.

One or more arcuate cam means 30, 31, 32, etc., are indicated on the ends of plate cylinder 10 and at the periphery thereof, and as having outwardly extending cam surfaces 34, 35, etc., positioned to contact the various inking and fountain rolls 12, 13, and 2326 during rotation of plate cylinder 10 and in a manner to move the inking and fountain rolls out of contact with the printing plate on the surface of cylinder 10 during that portion of the rotation thereof indicated by the circumferential extent of cam surfaces 34, 35, etc., with the radial movement of the axes of the inking and fountain rolls being accommodated by the conventional mounting means therefor in the printing press.

In order to select the particular part of the rotation of cylinder 10 during which the inking and fountain rolls are to be moved out of contact therewith, cam members 30, 31, 32, etc., are preferably provided with angular slots such as 36, with the cam members being afiixed to the ends of cylinder 10 as by bolts 37 engaging cylinder 10 through slots 36 so that the angular positioning of cam surfaces 34, 35, etc., can be moved or adjusted variously around cylinder 10 simply by loosening bolts 37 and sliding the cam members to the desired positions before tightening bolts 37 again in slots 36. Such an arrangement for affixing cam members to the plate cylinder 10 also provides for the simple and easy replacement of the cam members with other cam members having outwardly extending cam surfaces of a greater or less angular extent as may be required for the accommodation and applica tion of this invention to different sizes of printing images and sheets to be printed.

As will be more apparent from FIG. 2, the various cam members Sit-32, etc., preferably engage the inking and fountain rolls beyond the ends thereof and in an area of the stub shaft or mounting boss 40 thereof. Also, as indicated in FIG. 2, there is preferably provided on shaft 40 of the inking and fountain rolls such as 12, etc., a ball bearing cam follower arrangement having a collar 41 on shaft 40 of the roll around which freely rotates cam follower surface 42 by means of ball bearings indicated at 43. In such a manner, slippage or peripheral speed differences as between roll 12 and plate cylinder 10 are avoided or compensated for.

That is, roll 12 is driven, in conventional manner, by contact between roll 14 and plate cylinder 10 at a predetermined peripheral speed with respect to that of plate cylinder 10. As the ends of roll 12, however, ride up on cam surface 34 of earn means 30, the increased effective diameter provides a longer peripheral distance to travel than if the surface of roll 12 were in contact with the surface of cylinder 10. Nevertheless, the arrangement indicated with regard to the ball bearing cam follower 41-43 provides for the passage of roll 12 over the outwardly extending cam surface 34 without a necessary change in peripheral speed of roll 12, although a somewhat similar compensation is accomplished without such a rotating collar by having the contacting cam and roll surfaces smooth enough to slip readily against each other.

The effect of slippage with respect to plate cylinder 10 may be more noticeable with the inking rolls 23--26 than with the fountain rolls 1213, with such differences of peripheral speed or slippage becoming apparent by nonuniform inking of the plate on cylinder 10 when inking rolls 23-26 again contact the plate on cylinder 10 after having passed over cam surfaces 34, 35, etc. In this connection, as will be understood, the particular arrangement illustrated in FIG. 2 with regard to roll 12 preferably is repeated and exists with respect to each of the fountain and inking rolls 1213 and 2326, although, for clarity and to avoid repetition in the drawings, only one such arrangement is illustrated in FIG. 2.

Additionally, should it be desired to have the various moistening and/or inking rolls 1213 and 2326 individually and selectively moved out of contact with the surface of the printing plate on cylinder 10 at different times and/ or for different lengths of time and during different portions of the rotation of cylinder 1tldepending upon the particular size and distribution of image areas to be printed on the surface of the printing placea plurality of cam members 30, 31, 32, etc. (having, if desired, cam surfaces of different shapes or angular extents) are arranged axially spaced from one another as indicated in FIG. 2, and the ball bearing cam follower arrangement 4l-43 is then preferably positioned axially at the differ ent points on the stub shaft 40 of the several inking and fountain rolls so that, as will be understood, the cam follower on one roll will contact, for example, cam member 30 (as illustrated in FIG. 2), While the cam follower arrangement on another roll will be axially spaced further to the right in the drawing so as not to contact cam member 30, but, instead, cam member 31 or 32, etc. To this end there are also provided notches 45 spaced along the shafts 40 of the various rolls, with each notch 45 axially aligned with one of the several spaced cam members 3032, etc. In this manner, collar 41 of the cam follower arrangement may be slid axially along shaft 40 into a position thereon in which the cam follower will contact the desired cam member, and, preferably, with a spring pin or set screw 46 in collar 41 to engage a particular selected one of the notches 45 to align axially the cam follower on a particular roll with the particular cam member desired.

As will be apparent from the foregoing, there is thus provided in accordance herewith economical and mechanically simple means for selectively moving one or more of the various fountain and/ or inking rolls of an offset printing press individually or together out of surface contact with the surface of a printing plate on the plate cylinder for selected and adjustable portion only of the rotation thereof. In this manner there is avoided completely or partially the application of fountain solution and/ or printing ink to selected unused or image-free portions of the printing plate as may be desired in accordance with the placement of an image to be printed thereon, in order to avoid undesired mixing or application of either ink or fountain solution, yet the foregoing is readily accomplished without slippage or other non-uniformity in inking application to the areas of the printing plate to be printed and without otherwise disrupting or interfering with the normal or conventional operation of the printing press in the printing of material of widely different sizes.

While the methods and form of apparatus herein described constitute a preferred embodiment of the invention, it is to be understood that the invention is not limited to these precise methods or forms of apparatus, and that changes may be made therein Without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a lithographic printing press of the character described having a rotating plate cylinder carrying therearound a printing plate and a plurality of inking and moistening rollers spaced around the periphery of said plate cylinder for contacting said printing plate to spread sequentially films of aqueous fountain solution and printing ink thereon, the combination which comprises a plurality of cam means mounted around the periphery of said plate cylinder at the ends thereof and axially spaced E5 from each other for urging ditferentones of said rollers out of contact with the surface of said printing plate during selected different portions of the rotation of said plate cylinder, individual cam follower means on said rollers and axially spaced thereon for contacting different ones of said cam means effecting said urging of said rollers away from said plate cylinder, and said individual cam follower means being mounted directly on said rollers and extending coaxially from the ends thereof for free rotation with respect thereto to compensate for differential peripheral speeds between said rollers and said plate cylinder during that portion of the rotation thereof in which said rollers are urged out of contact with the surface of said plate cylinder.

2. In a lithographic printing press of the character described having a rotating plate cylinder carrying therearound a printing plate and a plurality of inking and moistening rollers spaced around the peripheryot said plate cylinder for contacting said printing plate to spread sequentially films of aqueous fountain solution and print ing ink thereon, the combination which comprises a plurality of cam means mounted around the periphery of said plate cylinder at the ends thereof and axially spaced from each other for urging different ones of said rollers out of contact with the surface of said printing plate during selected different portions of the rotation of said plate cylinder, individual cam follower means on said rollers extending coaxially from the ends thereof for contacting said cam means eflecting said urging of said rollers away from said plate cylinder, and said cam follower means being axially adjustable with respect to said rollers providing for individual selection of a particular said roller to be urged out of contact with said plate cylinder by a particular one of said axially spaced cam means.

3. In a lithographic printing press of the character described having a rotating plate cylinder carrying therearound a printing plate with an image to be printed thereon and a plurality of inking and moistening rollers spaced around the periphery of said plate cylinder for sequentially contacting said printing plate to spread sequentially films of aqueous fountain solution and printing ink selectively on said image and on non-image background areas of said printing plate, the combination which comprises means for urging said rollers out of contact with the surface of said printing plate and including cam means on said plate cylinder extending radially upwardly and beyond the surface thereof for individually contacting selected ones of said rollers urging said rollers radially outwardly away from the surface of said printing plate on said plate cylinder during selected portions of the rotation thereof, cam follower means on selected ones of said rollers for contacting said cam means, and means for adjusting the angular positioning of said cam means around said plate cylinder for selecting the portion and extent of rotation of said plate cylinder during which said rollers are urged out of contact with said printing plate depending upon the positioning and the size of said image on said printing plate.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A LITOGRAPHIC PRINTING PRESS OF THE CHARACTER DESCRIBED HAVING A ROTATING PLATE CYLINDER CARRING THEREAROUND A PRINTING PLATE AND PLURALITY OF INKING AND MOISTENING ROLLERS SPACED AROUND THE PERIPHERY OF SAID PLATE CYLINDER FOR CONTACTING SAID PRINTING PLATE TO SPREAD SEQUENTIALLY FILMS OF AQUEOUS FOUNTAIN SOLUTION AND PRINTING INK THEREON, THE COMBINATION WHICH COMPRISES A PLURALITY OF CAM MEANS MOUNTED AROUND THE PERIPHERY OF SAID PLATE CYLINDER AT THE ENDS THEREOF AND AXIALLY SPACED FORM EACH OTHER FOR URGING DIFFERENT ONES OF SAID ROLLERS OUT OF CONTACT WITH THE SURFACE OF SAID PRINTING PLATE DURING SELECTED DIFFERENT PORTIONS OF THE ROTATION OF SAID PLATE CYLINDER, INDIVIDUAL CAM FOLLOWER MEANS ON SAID ROLLERS AND AXIALLY SPACED THEREON FOR CONTACTING DIFFERENT ONES OF SAID CAM MEANS EFFECTING SAID URGING OF SAID ROLLERS 